1. Field of the Invention
The present invention relates to an apparatus and a method for supporting a Hot Plug Detect (HPD) function. More particularly, the present invention relates to an apparatus and method for supporting an HPD function in a portable terminal using High Definition Multimedia Interface (HDMI).
2. Description of the Related Art
With the rapid enhancement of digital products, several trends are underway, such as integration. More specifically, interfaces which connect between digital video apparatuses have been combined and complicated functions of the digital video apparatuses are becoming simplified. For example, a High Definition Multimedia Interface (HDMI) is becoming popular as a digital interface.
The HDMI is an interface for transferring digital video data including motion picture data and audio data. The HDMI supports high definition video data communication between an apparatus for transferring digital video data, such as a set top box (e.g., apparatuses for video transferring), a High Definition (HD) player (e.g., an HD-Digital Video Disc (DVD), Blu-ray, and the like), a digital television (TV), a computer, a camcorder and a camera, and an apparatus for displaying, such as a video display apparatus (i.e., Cathode Ray Tube (CRT)), a monitor, a braun tube TV, a Liquid Crystal Display (LCD) TV and a Plasma Display Panel (PDP) TV.
A digital video data transferring apparatus, which has transmitting and receiving chips and connectors for HDMI, outputs HD video data to a display apparatus through a dedicated HDMI cable.
FIG. 1 illustrates a conventional connection between video transferring apparatuses, such as a camcorder or a camera.
Referring to FIG. 1, a camcorder or a camera 100 and a display apparatus 110 are connected through an HDMI cable 120. The camcorder or the camera 100 records or plays video data and outputs a video signal to the display apparatus 110 using the HDMI.
The camcorder or the camera 100 includes a multimedia modem 102 that encodes the video signal. The display apparatus 110 receives the video signal from the camcorder or the camera 100 through the HDMI cable 120 and displays corresponding video data to a screen.
According to the type of HDMI cable, a connector pin number of the HDMI cable 120 may be 19 pins or 29 pins. An 18th pin of the connector with 19 pins is used for +5V and a 19th pin of the connector with 19 pins is used for a Hot Plug Detect (HPD) function.
When the camcorder or the camera 100 and the display apparatus 110 are connected through the HDMI cable 120, the camcorder or the camera 100 outputs +5V to the display apparatus 110 using the 18th pin. The camcorder or the camera 100 then determines whether the +5V is normally fed back using the 19th pin. That is, when the +5V is supplied by the camcorder or the camera 100 to the display apparatus 110 through the HDMI cable 120, the display apparatus 110 directly feeds back the +5V to the camcorder or the camera 100 using an HPD line 104.
The camcorder or the camera 100 determines that the connection through the HDMI cable 120 is normal when the feedback voltage is +5V. Accordingly, the camcorder or the camera 100 outputs video data to the display apparatus 110 and the display apparatus 110 displays the video data
The camcorder or the camera 100 determines that the connection through the HDMI cable 120 is not normal when the feedback voltage is not +5V. Thus, the camcorder or the camera 100 does not output the video data to the display apparatus 110.
A resistor (R2) 108 is a pull down register that stabilizes a voltage together with a resistor (R1) 106. The HPD line 104 of the multimedia modem 102 operates in a voltage range from +3V to +5.3V. A constant voltage of +3.3V is supplied to the HPD line 104 by R1 106 and R2 108.
Most portable terminals have camera modules so that it is possible to take a picture and record video data. Recently, a multimedia modem is installed in the portable terminal so that it is possible to process a high definition video and to output high definition video data and pictures to a display apparatus when there is support of an HDMI function in the portable terminal.
However, a communication modem is installed in the portable terminal besides the multimedia modem. Thus, it is necessary to support an HPD function for confirming the connection by the communication modem when the display apparatus is connected to the portable terminal. In the conventional technology, it is not necessary to support the HPD function in the portable terminal. However, it is necessary to support the HPD function according to the installment of the multimedia modem.
Therefore, a need exists for an apparatus and method for supporting an HPD function in a portable terminal using HDMI.